1. Field of the Invention
The present invention relates to an active matrix liquid crystal display (LCD) apparatus.
2. Description of the Related Art
Active matrix LCD apparatuses formed by liquid crystal cells and thin film transistors (TETs) have adopted polarity reversion driving systems to improve the picture quality such as the contrast and response speed for moving pictures. As a result, such LCD apparatuses have been broadly used in portable personal computers, desktop personal computers and the like.
For example, a pixel of a gate storage type LCD apparatus is formed by a liquid crystal cell connected to a common counter electrode, a TFT connected between a drain line and the liquid crystal cell, and a storage capacitor between the liquid crystal cell and a gate line adjacent to a gate line of this pixel. In this case, usually, since the capacitance of the storage capacitor is definite, a feed-through voltage fluctuates in the apparatus. Particularly, as LCD aparatuses have been increased in size and numerical aperture, and fine-structured, so that the width of the gate lines is reduced to increase the resistance thereof, the feed-through voltage greatly fluctuates. This will be explained later in detail.
In order to reduce the fluctuation of the feed-through voltage array, the resistances of the gate lines can be reduced. For example, the thickness of the gate lines can be reduced, and also, the gate lines can be made of material such as aluminum or gold having a low resistance. However, if the thickness of the gate lines is increased or the gate lines are made of the above-mentioned material, the manufacturing steps have to be changed.
Also, in a prior art LCD apparatus, the sizes of TFTs are gradually increased, thus compensating for the in-plane-fluctuation of the feed-through voltage (see JP-A-3-306221). This will also be explained later in detail. In this prior art LCD apparatus, however, the leakage current of the TFTs is increased.